In Vitro Neutralization Is Not Predictive of Prophylactic Efficacy of Broadly Neutralizing Monoclonal Antibodies CR6261 and CR9114 against Lethal H2 Influenza Virus Challenge in Mice

• Published in: Journal of virology Vol. 91; no. 24
• Main Authors: Sutton, Troy C, Lamirande, Elaine W, Bock, Kevin W, Moore, Ian N, Koudstaal, Wouter, Rehman, Muniza, Weverling, Gerrit Jan, Goudsmit, Jaap, Subbarao, Kanta
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 15-12-2017
• Subjects: Animals; Antibodies, Monoclonal - administration & dosage; Antibodies, Monoclonal - genetics; Antibodies, Monoclonal - immunology; Antibodies, Neutralizing - administration & dosage; Antibodies, Neutralizing - genetics; Antibodies, Neutralizing - immunology; Antibodies, Viral - administration & dosage; Antibodies, Viral - immunology; Cross Reactions; Hemagglutinin Glycoproteins, Influenza Virus - immunology; Humans; Influenza A Virus, H2N2 Subtype - immunology; Influenza A Virus, H2N2 Subtype - pathogenicity; Influenza, Human - immunology; Influenza, Human - prevention & control; Mice; Neutralization Tests - standards; Orthomyxoviridae Infections - immunology; Orthomyxoviridae Infections - prevention & control; Receptors, IgG - deficiency; Receptors, IgG - genetics; Receptors, IgG - immunology; Vaccines and Antiviral Agents; influenza; H2 influenza virus; in vivo evaluation; antibody function; influenza vaccines; prophylaxis; broadly neutralizing antibodies
• ISSN: 0022-538X; 1098-5514
• DOI: 10.1128/JVI.01603-17

Influenza viruses of the H1N1, H2N2, and H3N2 subtypes have caused previous pandemics. H2 influenza viruses represent a pandemic threat due to continued circulation in wild birds and limited immunity in the human population. In the event of a pandemic, antiviral agents are the mainstay for treatment, but broadly neutralizing antibodies (bNAbs) may be a viable alternative for short-term prophylaxis or treatment. The hemagglutinin stem binding bNAbs CR6261 and CR9114 have been shown to protect mice from severe disease following challenge with H1N1 and H5N1 and with H1N1, H3N2, and influenza B viruses, respectively. Early studies with CR6261 and CR9114 showed weak
activity against human H2 influenza viruses, but the
efficacy against H2 viruses is unknown. Therefore, we evaluated these antibodies against human- and animal-origin H2 viruses A/Ann Arbor/6/1960 (H2N2) (AA60) and A/swine/MO/4296424/06 (H2N3) (Sw06).
, CR6261 neutralized both H2 viruses, while CR9114 only neutralized Sw06. To evaluate prophylactic efficacy, mice were given CR6261 or CR9114 and intranasally challenged 24 h later with lethal doses of AA60 or Sw06. Both antibodies reduced mortality, weight loss, airway inflammation, and pulmonary viral load. Using engineered bNAb variants, antibody-mediated cell cytotoxicity reporter assays, and Fcγ receptor-deficient (
) mice, we show that the
efficacy of CR9114 against AA60 is mediated by Fcγ receptor-dependent mechanisms. Collectively, these findings demonstrate the
efficacy of CR6261 and CR9114 against H2 viruses and emphasize the need for
evaluation of bNAbs.
bNAbs represent a strategy to prevent or treat infection by a wide range of influenza viruses. The evaluation of these antibodies against H2 viruses is important because H2 viruses caused a pandemic in 1957 and could cross into humans again. We demonstrate that CR6261 and CR9114 are effective against infection with H2 viruses of both human and animal origin in mice, despite the finding that CR9114 did not display
neutralizing activity against the human H2 virus. These findings emphasize the importance of
evaluation and testing of bNAbs.